Instrument board for automobiles



Dec. 17, 1929. DU PONT 7 1,739,954

' INSTRUMENT BOARD FOR AUTOMOBILES Filed Feb. 9, 1927 Patented Dec. 17,1929 PATENT OFFICE FRANCIS I. DU FONT, OF WILMINGTON, DELAWAREINSTRUMENT noAnn r03. AUTOMOBILES Application filed February 9, 1927.Serial No. 166,962.

My invention relates to an improvement in instrument boards forautomobiles and more particularly to means whereby the instruments maybe efficiently illuminated at night without the production of any glaretending to interfere with the vision of the operator.

As is well known the several instruments, as an oil gauge, ammeter,speedometer, etc., necessary for indicating conditions during theoperation of an automobile, are usually mounted on an instrument boardpositioned in front of the operator, and it is quite customary to groupthe instruments, the group being positioned behind a pane or sheet ofglass 5 let into the instrument board. In order that the instruments maybe visible to the operator of an automobile at night, it is customary toprovide a lamp so positioned as to throw light on the instruments.However, as is well known, the lamp, if positioned to effectively lightup the instruments, also causes more or less glare with the result thatthe operators vision ahead is materially impaired.

Heretofore numerous efforts have been made to avoid the glar from theso-called dash light, but such have been substantially unsuccessful, ithaving been found that where glare has been reduced the uniform andeffective lighting of the instruments has been correspondingly reduced.

Now it is the object of my invention to provide means whereby theinstruments carried by the instrument board of an automobile may beuniformly and efficiently illuminated without the production of glare.

Having now indicated, in a general way, the nature and purpose of myinvention, I will proceed to a detailed description thereof withreference to the accompanying drawings in which I have illustrated apreferred embodiment and in which 2- Fig. 1 is a front view of aninstrument board embodying my invention, the end portions being brokenaway.

Fig. 2 is a sectional view on line 22, Fig. 1.

Fig. 3 is a sectional view on line 3-3, Fig. 1.

In the drawings a indicates an instrument board such as is usuallyprovided in an auto mobile. The board a is provided with a recess of anydesired shape, for example, an

elliptical recess as shown in Figure 1, into which is fitted a sheet orplate I) of glass, suitable means heing provided for retaining the platein place.

The plate of glass 1), preferably of elliptical shape and the edges ofwhich are preferably silvered as indicated at m, Figs. 2 and 3, orotherwise made reflective, is provided adjacent its upper edge andmidway between its ends with an aperture 0 in which is positioned anelectric lamp 03, mounted in a socket 6, extending through a suitableaperture in and supported by the instrument board. The lamp is connectedto an electric circuit through wires The wall of the aperture 0 may becylindrical, though it is preferable that it be made tapering for adistance from the front and back of the plate, as shown at 11 Fig. 2,and cylindrical in the central portion, as shown at a, Fig. 2. Thetapered portions 7 of the wall of the aperture 0 are at such an anglethat rays from the lamp entering the body of the plate I) will extendindirections such that they will strike the face of the plate at anglesof total reflection. The front of the aperture 0 is closed by means of acover 9 pivotally attached to a casing it provided with spring lugs iadapted to extend into the aperture and engage the wall thereof tomaintain the casing and cover in position.

In the rear face of plate 6 below the aperture c, is formed a relativelycircular recess y', the walls of which are vertical and the bottom ofwhich is convex, as shown at is, Fig. 2. On opposite sides of theaperture 0 are formed relatively small circular recesses j havingvertical walls and convex bottoms is, while adjacent the recesses j areformed further circular recesses j having vertical walls and convexbottoms 7c". The recesses y' are made deeper than the recesses j, whichare positioned between the recesses j and the aperture 0 in which ispositioned the lamp d.

Various instruments extend through suitable apertures formed in theinstrument board a in line with the several recesses and are supportedby the board in line with the apertures and immediately adjacent therear face of the plate I). For example, a speedometer Z is supportedwith its dial concentric with the recess j, while, for example, an oilpressure gauge at and a" clock a are supported with the dials in linewith the recesses j and, for example, an amineter o and a gasoline gauge2 are supported with their dials in line with the apertures j".

Against the rear face of the plate Z2 is positioned a mat g, aperturedin line with the several recesses. The mat 9 may be of any desiredmaterial, a paper or cloth and is preferably black, or of a color whichwill contrast with the dials of the instruments.

In the operation of the embodiment of my invention above described, ifthe lamp d, which is positioned in the aperture 0 in the glass plate 6,be lighted, the rays therefrom will be prevented from extendingforwardly by the cover 9 and from extending rearwardly by the'socket 6.Thus the effective rays emanating from the lamp will strike the wall ofthe aperture 0 in the plate and will pass therethrough into the body ofthe plate. Since the wall of the aperture 0 is tapered adjacent thefrontand rear faces of the plate, those rays which pass through the wallof the aperture adjacent the faces of the plate will, due to theangularity of the tapered surfaces of the wall, pass into the body ofthe plate in a direction such that they will respectively strike thefaces of the plate at an angle at which on tending to pass from a densermedium, the plate, to a lighter medium, the atmosphere, they will betotally reflected from the surface back into the body of the plate.Should any of the rays from the lamp tend to pass out of the sheet ad-'jacent the forward end of aperture 0, such will be masked by the casingh and the extension of rays from the front of the plate will beprevented. The rays from thelamp reflected from the faces of the platewill travel longitudinally through the body of the plate. beingreflected from face to face. The rays from the lamp which strike thecylindrical central portion of the wall of the aperture will travellongitudinally of the plate. Thus the rays of light from the lampentering the plate athrough the walls of the aperture 0 will travel inall directions from the aper-- ture 0 toward the edges of the plate.from which, since the edges are silvered, the rays reaching the edgeswill be reflected back into the body of the plate. If the edges beclear, the rays reaching them will pass out of the plate, but such willnot cause any glare since the edges of the plate are masked by the wallsof the recess in the instrument board in which the plate is positioned.

As explained above, rays of light from the lamp d are caused to travelthrough the body of the plate toward its edge, some directly and othersdue to reflection from face to face of the plate, the result of strikingthe faces at an angle of total reflection. Certain of the rays travelindirectly. through the body of the plate wil strike the walls of therecesses j and j" and will pass out of the body of the plate and inpassing from a dense to a lighter medium will by refraction' be directedtoward the convex bottoms la, is of the recesses from which the rayswill be reflected on to the dials of the instruments l, o and 32. Otherrays reflectedv from face to face of the plate will reach the surface ofthe convex bottoms of the recesses I at an angle at which they will berefracted rather than reflected thereby and such rays will pass out ofthe bod of the plate and be directed toward the dials of theinstruments, or pass back. into the body of the plate through the wallsof the recesses. Those rays which pass out of the body of the plate fromthe walls or bottom of the recesses will be directed toward the dials ofthe instruments and will adequately and etficiently light them up,without causing any glare from the front of the plate through the frontsurface of which no rays pass out.

The walls and bottoms of the recesses 7' act to direct the light raysstriking them in the same manner as do the walls and hot toms of therecesses j and j" and since the depth of the recesses 7' is greater thanthe depth of the recesses j, which lie between recesses j" and thelight, ample light will pass through the body of the plate between thebottoms of recesses j and the front surface for an adequate lighting ofthe instruments at and a. Further light will reach the walls of therecesses j" by reflection from the edge of the plate, if it be madereflective, as by silvcring.

It will now be observed that by virtue of my invention, the instrumentscarried by an instrument board of an automobile may be efliciently and,if desired, brilliantly lighted without the production of the slightestglare from the surface thereof.

It will be understood that I do not intend that my invention shall belimited in scope to the details of construction of the embodimentthereof above described, since it will be obvious that variousmodifications may be made without departing from the spirit of myinvention. It will be understood that the light rays may. be introducedinto the body of the plate a at more than one pointv or through an edgethereof and that the several recesses in the plate may beof thesamedepth or a single recess may be provided for the accommodation of aplurality of instruments, and it will also be understood that theangularity of the walls of the recesses and the form of the bottoms maybe varied so long as variations does not result in the refraction oflight from the front face of the plate.

Having now fully described my invention,

what I claim and desire to protect by Letters Patent is 1. In aninstrument board for automobiles, in combination, a sheet of glasshaving a plurality of recesses of varying depth formed therein,instruments supported adjacent to and facing the open ends of saidrecesses, an aperture in said sheet the walls of which adjacent thefront and back surfaces of said sheet extend at an angle to theintermediate ortion thereof, and a lamp positioned in said aperture.

2. In an instrument board for automobiles, in combination, a sheet ofglass having a plurality of recesses of varying depth formed therein,instruments supported adjacent to and facing the open ends of saidrecesses, an aperture in said sheet the Walls of which adjacent thefront and back surfaces of said sheet extend at an angle to theintermediate portion thereof, a lamp positioned in said aperture andmeans for masking said lamp to prevent rays of light therefrom fromextending from the front face of said sheet.

3. In an instrument board for automobiles, in combination, a sheet ofglass having a plurality of recesses of varying depths formed therein,instruments supported adjacent to and facing the open ends of saidrecesses, a circular aperture the wall of which is tapered outwardlyfrom points spaced from the front and back faces of said sheet, a lamppositioned in said aperture and means for masking said lamp to preventrays of light therefrom from extending from the front face of saidsheet.

4. An illuminating means for an object, comprising a transparent sheethaving its rear face placed in front of the object and through which theobject may be viewed, a source of light, a transverse surface of saidsheet positioned so that rays from said source of light may pass throughsaid transverse surface'into the sheet and between the faces thereof,and means for directing some of said rays passing through said sheetupon the object.

5. An illuminating means for an object, comprising a transparent sheetthrough which the object may be viewed having its rear face in front ofthe object, means for projecting rays of light through the sheet andbetween the faces thereof at such angles that projected rays whichstrike the front face of the sheet in front of the object will betotally reflected into the sheet from said front face, and means fordirecting rays passing through said sheet upon the object.

6. An illuminating means for an object, comprising a transparent sheetthrough which the object may be viewed having its rear face in front ofthe object, means for projecting rays of light through the sheet andbetween the faces thereof at such an les that projected rays strike thefront face of the sheet in front of the object at angles of incidencenot substantially less than the critical angle, and means for directingrays passing through said sheet upon the object.

7. An illuminating means for an object comprising a transparent sheetthrough which the object may be viewed having its rear face in front ofthe object, means for projecting rays of light through the sheet andbetween the faces thereof, said sheet having a surface between theplanes of its front and rear faces for directing rays passing throughthe sheet upon the object.

8. An illuminating means for a plurality of objects, comprisingatransparent sheet through which the objects may be viewed having itsrear face in front of the objects, means for projecting rays of lightthrough the sheet in paths extending in the direction of its faces, saidprojecting means being located in alignment with the objects,intercepting means for directing some of said rays upon the objectnearer to the projecting means, and means for directing rays notintercepted by the said intercepting means upon the object farther fromthe projecting means.

9. An illuminating means for an object, comprising a transparent sheetthrough which the object may be viewed having its rear face in front ofthe object, means for projecting rays of light through the sheet andbetween the faces thereof, and means located between the planes of thefaces of said sheet to intercept rays passing through the sheet anddirect them upon the object.

10. An illuminating means for an object, comprising a transparentmember, through which the object may be viewed in front of the object,said transparent member having a plane front faceand a rear face,portions of which rear face in front of the object form acute angleswith the plane of the front face, and means for projecting rays of lightupon the portions of acute angle of said rear face whereby they arereflected upon the object.

I 11. An illuminating means for an object, comprising a transparentsheet through which the object may be viewed having its rear face infront of the object, means for projecting rays of light through thesheet and between the faces thereof, means located between the planes ofthe faces of said sheet to intercept rays passing through the sheet anddirect them upon the object, and means for reflecting rays at transverseedges of the sheet back through the sheet.

12. An illuminating means for an-object, comprising a transparent sheetthrough which the object may be viewed having its rear face in front ofthe object and having'a transverse convex edge portion, means forprojecting rays of light through the sheet and between the facesthereof, means located between the planes of the faces of said sheet tointercept rays passing through the sheet and direct them upon theobject, and means for reflecting rays at the transverse convex edgeportion back through the sheet.

In testimony of which invention, I have hereunto set my hand, atPhiladelphia," Penna., on this 7th day of February, 1927.

FRANCIS I. DU PONT.

